title: Isoproterenol accelerates apoptosis through the over-expression of the sodium/calcium exchanger in HeLa cells.
abstract: Apoptosis induction causes over-expression of the Na+/Ca2+ exchanger of type 1 (NCX1) in the HeLa cell line. During induction of apoptosis and in the presence of isoproterenol hydrochloride (I; β-adrenergic agonist), increase in the NCX1 is even more pronounced. Anti-apoptotic Bcl-2 mRNA and protein is markedly reduced during apoptosis and in the presence of I, which causes a rapid increase in the Bax/Bcl-2 ratio. During apoptosis induction by apoptosis inducing kit (A), both with and without I, the active form of caspase-3, which is the executive enzyme in apoptosis, becomes visible on Western blots. Silencing NCX1 resulted in the reversal of the Bax/Bcl-2 ratio, it prevented a decrease in mitochondrial membrane potential compared to the AI group and it decreased the level of AI-induced apoptosis in HeLa cells. Based on the experiments with single apoptotic inducers camptothecin, cycloheximide and dexamethasone, it might be proposed that potentiated apoptotic effect in I-treated cells is due to the inhibition of nuclear topoisomerase. As illustrated in immunofluorescence and Western blot analysis, calnexin increased significantly during induction of the apoptosis in the presence of I. In addition, further decrease in sarco/endoplasmic ATPase 2 (SERCA2), decrease in reticular calcium and mitochondrial membrane potential was observed, which suggests development of the endoplasmic reticulum (ER) stress. Based on these results, we propose that I further enhanced NCX1 expression in apoptotic cells through the development of ER stress.
authors.affiliation: Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovak Republic.
authors.forename: Sona
authors.initials: S
authors.lastname: Hudecova
authors.forename: Lubomira
authors.initials: L
authors.lastname: Lencesova
authors.forename: Lucia
authors.initials: L
authors.lastname: Csaderova
authors.forename: Jan
authors.initials: J
authors.lastname: Sedlak
authors.forename: Viera
authors.initials: V
authors.lastname: Bohacova
authors.forename: Marcela
authors.initials: M
authors.lastname: Laukova
authors.forename: Olga
authors.initials: O
authors.lastname: Krizanova
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002166:Camptothecin / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D006367:HeLa Cells; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000235:genetics*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000318:Adrenergic beta-Agonists; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D019831:Sodium-Calcium Exchanger; D051028:bcl-2-Associated X Protein; C110374:sodium-calcium exchanger 1; D003513:Cycloheximide; D053148:Caspase 3; D007545:Isoproterenol; D002166:Camptothecin